Nick Kyrgios has defied injury to surge into the third round of the US Open with a serving masterclass.

Kyrgios showcased some substance to complement his undoubted style in sweeping past Horacio Zeballos 7-5 6-4 6-4 in one hour and 56 minutes on Thursday night.

Despite battling a painful hip flexor injury, the 14th seed was untouchable on serve, belting 27 aces and not offering his Argentine opponent a solitary break-point.